1978: PhD at the University of Amsterdam. Promotor (supervisor): Prof.dr. H.J. Drossaart Lulofs. Title of dissertation: The Arabic Version of Aristotle's Parts of Animals. Book XI-XIV of the Kitâb al-Hayawân; a critical edition with introduction and selected glossary.

Professional career:

August 1967-December 1969: research fellow, later assistant professor, at the University of Leiden.

January 1969-January 1990: Assistant professor, later associate professor, at the University of Utrecht.

February 1990-October 2007: Full professor of Arabic Language and Culture at the University of Leiden.